1. Field of the Invention
The present invention relates to a keying system for combining a foreground image and a background image into a composite image, and a method of producing the composite image, which are used in, for example, a virtual studio or the like. More particularly, the present invention relates to a keying system, whose system configuration is simplified, and to a method of producing the composite image easily.
2. Description of the Related Art
In a studio or the like of a television station, a set built from sceneries (or scenes) and so on is provided behind a performer such as an announcer. The set which has been once built, should be kept in a suitable place until used next time. Hence, the problems of how to secure the safekeeping place and how to raise safekeeping expenses have arisen.
Thus, there has been known a chroma-key system wherein a virtual set is made as a background image by a high-performance computer having a high-speed graphics processing function by which a real-time rendering and a real-time texture mapping and so forth can be achieved, and whereby this background image and a foreground image obtained by taking an image of an object such as an announcer are combined by keying to realize a virtual studio.
In the case of this system, for instance, the image of the announcer, who is reading news in front of a blue screen for a chroma key in a studio of a television station or the like, is taken as the foreground image by a television camera and so on. Subsequently, a background image generated in real time as a result of a graphics processing performed by the high-performance computer is superimposed on this foreground image. Then, the superimposed portion of the background image and foreground image is blanked out by keying process. Further, a composite image is obtained by fitting an object's image portion of the foreground image into the blank portion. As a consequence, the foreground and background images can be shown as if the object's image portion of foreground image (namely, the announcer) is placed in front or in rear of the background image (namely, the virtual set).
However, in the case of such a conventional chroma-key system, the background image is generated in real time, so that a costly high-performance computer having a high-performance processing CPU and high-performance image processing circuits must be used. Thus, there have been caused problems in that high-level running skills to run the costly high-performance computer by using complicated programs are needed. Moreover, the cost of the conventional chroma-key system becomes high because the cost of the high-performance processing CPU itself is high and, in addition, the cost of the high-performance image processing circuits is high owing to using an enormous circuit elements for performing the high-performance imaging process. Therefore, such a conventional chroma-key system cannot be used if not in a large-scale facility such as a key station.
Further, in the case of using the aforementioned high-performance computer, it is necessary to secure the safekeeping place and to raise maintenance expenses and personnel expenditures for employing engineers of sophisticated skills. Thus, problems similar to those in the case of using the actual studio which has the sets built from the scenes have arisen.
Judging from the current state-of-the-art in technologies, the aforementioned computer realizes advanced high-speed graphics processing functions. The aforementioned computer (system) is, therefore, in danger of coming down suddenly during the operation of the advanced high-speed graphic process. To avoid such danger, duplex high-performance computer systems should be provided, with the result that the cost is further increased.